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Thread: vent free

  1. #27
    Join Date
    Sep 2002
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    South Dakota
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    6,579

    Re: thanks

    Originally posted by nickm
    Thanks for the opinions. As far as oversizing is concerned my unit has a thermostat and adjust the flame accordingly. It does not seem to be a problem. It could use a cleaning. I will follow the manufacturers instructions and clean it properly. I would not want to depend on the unit to functions daily for my primary heat source but it seems to work fine for auxilary heat in the basement.

    I highly recommend that you purchase and install a carbon monoxide alarm!

  2. #28
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    Sep 2002
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    South Dakota
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    Originally posted by rich pickering
    What is the safe level for o2?

    21%


  3. #29
    Join Date
    Nov 2001
    Location
    Moose Jaw, Saskatchewan, Canada Occupation:Interprovincial Plumber, Commercial Gasfitter Interests:
    Posts
    2,412
    20.9?

    So, at what level will the pilot shut off?

    I love my job, but paydays Thursday

  4. #30
    Join Date
    Sep 2002
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    South Dakota
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    Originally posted by rich pickering
    20.9?

    So, at what level will the pilot shut off?


    Good question Rich. Let's let the CO and ventless experts who sell these things tell us the answer to that question.

    When they do, I have a series of additional questions that I would like them to answer.

    You see, at one time long, long ago when I did not know better I installed a few ventless systems. Then I got a little educated and having the open mind that I have, learned how potentially dangerous they actually are. For all the same reasons some of the better local building codes outlaw them.

    Norm

  5. #31
    Join Date
    Aug 2004
    Location
    S.E. Pa
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    6,137

    O2 levels

    Ambient air contains about 20.9% O2. People and fire both need about 16%. The ANSI Stds require an ODS shutoff at 18%. Some kickout at 18.5%. What happends is the flame spead slows to the point the flame has advanced past the thermocouple shutting it down. It does not cause a soft, yellow tipped flame to curl away from the TC--that's from a dirty primary air hole.

    So the theory is, as long as you have 18% O2 or more, you shouldn't be getting enough incomplete combustion to make significant levels of CO and aldehydes. That has been repeaterdly demonstrated in the lab. What has not happended is a scientific double blind field study of actual installations. As Norm points out, the original owners may be educated and conscientious. The future owners are an unknown. Also, maintenance tends to slide over time. People get accustomed to ambient odors in their homes.

    There are two distinct areas of concern:
    What's happening in the combustion zone?
    What's happening to the house as a whole? Therein lies the great debate. A highly touted study released to the industry at Nashville was based on computer modelling. It did not take into account what happens to the Rh% when room air migrates to cold areas such as closets on exterior walls? The air cools to dewpoint, the RH% goes up, and you get condensation. Ask any Canadian from B.C. about soggy closets and mold. Wall penetrations such as light switches can channel moisture into the interstitial spaces where it can condense out. Therefore, these studies need to account for such real world situations.

    Norm, my point about the courts was simply that until enough evidence is presented and sold to a court as in litigation, VF will continue. As long as someone can make money, they will continue selling it. Just look at jar candles. They've been sued a lot and lost. Still, the awards don't come close to the $5BILLION dollar industry/yr.

    Have a good one!

  6. #32
    Join Date
    Jan 2001
    Location
    Pacific Coast of Canada
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    4,008

    Re: O2 levels

    Originally posted by hearthman
    Ask any Canadian from B.C. about soggy closets and mold.


    Which is why we are ahead of the curve in two ways.
    1. We have some of the most stringent ventilation codes in North America.
    2. Ventless fireplaces are not allowed.

  7. #33
    Join Date
    Nov 2001
    Location
    Moose Jaw, Saskatchewan, Canada Occupation:Interprovincial Plumber, Commercial Gasfitter Interests:
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    2,412
    OSHA says that any level below 19.5% may be hazardous. At 19.5% there is 75,000 ppm of some other gas in the air. Here is an interesting link.
    http://www.occupationalhazards.com/s...le.php?id=1502
    I just can't get comfortable with vent-free.
    And gas ranges bother me too.
    I love my job, but paydays Thursday

  8. #34
    Join Date
    Jun 2005
    Posts
    12

    on and on and on

    I have continued to read all of your responses for the last few days and have not responded - just to see what everyone was saying. I think that all of your input has been extremely insightful and certainly from the heart. I myself prefer direct vent fireplaces and stoves and show that as a first option for a customer. Since I have EXTENSIVE experience in selling, using, and servicing vent free appliances, I can tell you that I have never encountered any of the EXTREME conditions that you elaborate on. I have never seen or experienced these conditions that you are so afraid of; and I know many people in our industry that have been selling the same types of vent free appliances for years and I have never heard of any of these conditions from any of them either. Even the moisture issue which I have heard about but have never witnessed, is a non-issue - maybe our region is cold and dry enough or maybe the problems are cumulative with other factors in a building such as shade, poor construction practices or just plain oversizing of an appliance.

    I am not saying that problems never occur, but it is far and few between and usually correctable with routine maintenance which we promote. Hey, there are plenty of sleazy companies out there and selling things they have no business handling, but in the right hands vent free can be a great option for a homeowner.

    Look, I am not trying to convert anyone to the Dark Side of the Force or anything, but don't make claims about products that you evidently have only cursory experience with. After you have a few hundred under your belt will you completely understand my perspective. I do not expect that to happen, but I won't bash things I don't know about 100%, and I only support things I know about 100%.

    My distinqushed colleague from HTH makes very good points with exact facts and raises concerns, but yet is only cautionary with regards to the vent free products. I am sure he also prefers the direct vent option and have no problem that. But he seems much more diplomatic about any concerns he may have.

    I say again that I respect all of your thoughts and questions on this subject and it re-enforces the need for careful qualification of every customer with any hearth appliance. Just as going through the NFI testing has made me more thoughtful and careful about every project I am involved in, so has the dialogue in this forum which is important. In order to be professional it is important not to ignore the training.

    Thank you for your input.


  9. #35
    Join Date
    Jan 2005
    Posts
    33
    Here is a great link that covers the topic of Lung Vented Gas Appliances.

    http://www.chimneysweeponline.com/hovntlss.htm

  10. #36
    Join Date
    Dec 2000
    Location
    Michigan
    Posts
    724

    Wink H20!

    What has not been discussed is the impact on indoor RH. Burning natural gas is the most efficient way to add water vapor to the air especially if the appliance is set up and operating correctly!

    With tight homes I have seen and read the impact on RH when the homeowner uses a non-vented fireplace. “Sarcastically” it is better then either a by-pass or powered humidifier for increasing the RH in a home!

    The quality of my performance, sometimes depends on the quality of my audience.
    Imitation (Plagiarism) is the best compliment one can get -- "Open A Window"

    To improve Indoor Air Quality: Control Indoor Air QUANTITY = "I.A.Q.Q."

  11. #37
    Join Date
    Apr 2002
    Posts
    1,383
    <<Quite frankly, I'm a helluva lot more afraid of Cat.1 water heaters and gas cook stoves. I have seen these backdraft easily. I have treated CO victims from gas ovens back when I was a paramedic. Why is it gas ovens are not required to interlock the exhaust fan to the burners? Heck, I've seen tons that don't even vent to the outdoors. They often now use those microwave/fans set up to recirculate and filter (joke) rather than exhaust.
    >>


    When I was a gas utility repairman, I investigated hundreds of complaints of possible carbon monoxide problems in homes and businesses.

    Gravity vented furnaces and boilers were the most dagerous offenders, since the combination of a plugged chimney, defective combustion and high gas consumption could put a lot of CO in a home.

    Water heaters can also be a problem, but produced relatively few actual problems. Even when the chimney was plugged, the burners tended to be relatively unlikely to produce a lot of CO.

    Oven burners tended to be a fairly common source of CO and aldehyde odors. And occasionally I'd find a range burner pilot light that was dirty and creating a considerable amound of CO in a small apartment.

    In my independent repair business, I testified as an expert witness for a homeowner in a new house who went to the hospital with CO poisoning. The unvented fireplace was installed by the general contractor, and the logs hadn't been installed correctly. That's all it took to send the woman to the hospital.

    The fireplace combustion gasses were producing about 60 PPM CO due to this defect in installation. When I installed the logs correctly, the CO produced was not measurable.

    When I was reading the directions for installing the logs, I found them complicated and very difficult to follow. I probably spent twenty minutes or more reading the instructions before I figured out how to do it. I'm sure the contractor installed the logs intuitively, which resulted in the injury of the homeowner.

    Personally, I generally refuse to service unvented equipment ---it's not worth the risk. If someone is injured, I would expect that anyone who has touched the equipment, even years earluier, will be sued. Who needs that kind of liability? That also probably contributes to added difficulties in getting servive for such equipment.

    Finally, I will concede that IF one follows ALL the instructions and warnings manufacturers provide with unvented equipment, they can no doubt be operated with a high degree of safety. But that means that I should be able to devise an examination based on the instruction manual which the owner will be able to pass. And any visitor or tenant should be able to pass that same examination at any time.

    As a practical matter, I've never found an owner or user of unvented equipment who was aware of all the details of how such a fireplace was operated, and therefore have never met someone who should be operating such equipment.

    The margin of safety is just too low, in my opinion. In theory, such equipment CAN be operated safely. In practice, people are running significant risks should the equipment malfunction.



    Seattle Pioneer


  12. #38
    Join Date
    Oct 2003
    Location
    pennsylvania
    Posts
    10
    I am also a repairman for a gas utility, ive seen many VF equipment that works without problems. No product can be made idiot proof. Alot of installers and consumers never look at the installation manual. Our biggest campaign now is innsufficient make up air in a building for the total btu load. Dryers are the biggest problem causing the negative pressure in a home. When you introduce a flame to a cold surface your going to produce co, example the diverter plate above the burner in a stove oven, not uncommon to have 800 ppm co on start up, thats why you should never use a oven for space heating, you should also crack open kitchen window on thanksgiving and christmas for those all day cooking events. Do I have a unvented space heater in my family room, Yup. I have plenty of make up air, unit is properly installed and maintained. The aldehyde odor is a dead give away of a problem, customers also need to be aware of using oil based products around an open flame, i see this all the time (smells like charcoal lighter fluid for the most part). They use wood preen, pledge, kids spray painting in the garage ect will cause it. If you use the fuel gas code book and installation booklet you should be ok. When i run the space heater i shut off my humidifier on the furnace, if i remember right a 100k btu used will discharge a gal of water vapor.

  13. #39
    Join Date
    Dec 2000
    Location
    Michigan
    Posts
    724

    Hmm H2O and more H2O and more H2O = 100% RH!

    Discussing this with my son (Chemical Engineer from U of M))this morning, burning CH4 for 100,000 BTU will generate approximately 1 gallon of water. Then if we assume at 70º F, the saturation water vapor density is about 0.0011 lbs/ft³. Then for a house with 18,000ft³of air, adding a gallon of water vapor will raise the RH from 30% to 72% (Norm can you confirm the math)

    Therefore, in addition to buying a CO detector, buy a hygrometer and watch the mold grow!

    This is the reason I never recommend a vent-less fireplace, but if you do, OPEN THE WINDOW for Combustion Air and Air Exchange to "Dry/Dilute" the inside RH!
    The quality of my performance, sometimes depends on the quality of my audience.
    Imitation (Plagiarism) is the best compliment one can get -- "Open A Window"

    To improve Indoor Air Quality: Control Indoor Air QUANTITY = "I.A.Q.Q."

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